Question

The dead burnt plaster is?

Answer 1

Dead burnt Plaster:

• Anhydrous calcium sulphate${\mathrm{CaSO}}_4$ is found in dead charred plaster.
• Calcium sulphate is an inorganic compound. In the form of $\mathrm{\gamma }-$anhydrite, it is used as a desiccant.
• It is referred to as dead burned because, when moistened with water, it does not set like the Plaster of Paris (${\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}$).
• When the Plaster of Paris is heated above $393\mathrm{K}$ its water of crystallization is lost and the leftover anhydrous calcium sulphate is called the dead burnt plaster.
• It has a remarkable property of setting with water.